Hands On System Design Course - Code Everyday

Hands On System Design Course - Code Everyday

Day 163: Build Service Dependency Mapping

May 10, 2026
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What We’re Building Today

Today we’ll create an automatic service dependency discovery system that analyzes log data to map how services communicate. By parsing API calls, database queries, and message queue events from logs, we’ll build a real-time dependency graph showing which services talk to each other, how frequently, and with what latency.

Key deliverables:

  • Log parser that extracts service interactions

  • Graph builder that constructs dependency relationships

  • Real-time visualization dashboard

  • Health impact analyzer


Core Concept: Service Dependency Mapping

Service dependency mapping answers a critical question: “If service X goes down, what else breaks?” In production systems like Netflix’s microservices architecture (over 700 services), understanding dependencies prevents cascading failures. When a video transcoding service fails, you need to know it impacts recommendations, search, and playback - not just video uploads.

How it works: Parse logs for interaction patterns (HTTP calls, RPC invocations, database connections), build a directed graph where nodes are services and edges are dependencies, weight edges by call frequency and latency, detect circular dependencies and single points of failure.

Why it matters: Uber processes 40 million rides daily across 1000+ microservices. Without dependency mapping, deploying a payment service update could unknowingly break ride matching. Automated discovery from logs eliminates manual documentation that’s always outdated.

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